1. Field of the Invention
The present invention relates to a circuit breaker, and more particularly, to a circuit breaker including a lug-type terminal block.
2. Background of the Invention
In general, a circuit breaker is an electrical device that manually opens and closes an electrical circuit by a handle, or that protects load devices and circuits by detecting an abnormal current such as a short current or a fault current and automatically breaking the circuits.
The circuit breaker normally maintains a conductive status when a rated current flows, but performs a breaking operation when a fault current occurs. To this end, a fixed contact and a moving contact maintain a closed status when a normal current flows.
However, when a fault current has occurred, a trip unit detects the fault current and transmits a signal to a switching mechanism. Then, the switching mechanism is released. Once the switching mechanism is released, the fixed contact and the moving contact are separated from each other. Accordingly, the circuit breaker is able to safely break the accident current.
The circuit breaker includes an arc suppressor on one side of the switching mechanism. The arc suppressor blows out and suppresses an arc generated when the fixed contact and the moving contact are separated from each other.
The circuit breaker is divided into a surface-type terminal block, a reversible terminal block, a plug-in type terminal block, and a lug-type terminal block, depending on the connecting method of a terminal block for connecting the wire of a power supply side and the wire of a load side.
The lug-type terminal block is usually used in the U.S. market.
FIG. 1 is a perspective view showing a conventional circuit breaker using a lug-type terminal block. FIG. 2 is a cross-sectional view taken along the line I-I of FIG. 1.
Hereinafter, the conventional circuit breaker using a lug-type terminal block will be described below with reference to the accompanying FIGS. 1 and 2.
That is, a main body 20 is placed within an outer casing 10 of the conventional circuit breaker.
A mechanism (not shown) including a fixed contact 40 and a moving contact 30, an arc suppressor 24, a trip unit (not shown), etc are mounted within the main body 20 for circuit breaking purposes.
A terminal portion 42 is formed on an end of the fixed contact 40 so as to be exposed to the exterior of the main body 20. A lug-type terminal block 50 for connecting the terminal portion 42 and a wire (not shown) is attached to the terminal portion 42.
The bottom side of the lug-type terminal block 50 is in contact with the terminal portion 42, and one side thereof is positioned facing the main body 20.
However, the lug-type terminal block 50 is positioned in proximity to the outer surface 22 of the arc suppressor 24 in the main body, so that the distance between them is fairly small. As such, an arc conduction path may be formed between the lug-type terminal block 50 and the arc suppressor 24 of the main body 20. Accordingly, dielectric breakdown might occur to the terminal portion through the lug-type terminal block in the main body.
Taking this into consideration, the terminal portion 42 and the lug-type terminal block 50 may be spaced far from the main body 20. In this case, dielectric breakdown can be suppressed. However, this requires increasing the size of the circuit breaker, thus leading to a rise in manufacturing costs and imposing limitations on installation space.